Family of multi-speed dual-clutch transmissions having four planetary gear sets and four brakes

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least six forward speed ratios and one reverse speed ratio. The transmission family members include four planetary gear sets, two input clutches, eight torque transmitting mechanisms, and three fixed interconnections. The invention provides a low content multi-speed dual clutch transmission mechanism wherein the two input clutches alternately connect the engine to realize odd and even number speed ratio ranges. The eight torque transmitting mechanisms provide connections between various gear members, the fixed interconnections, the input clutches, the output shaft, and the transmission housing, and are operated in combinations of three to establish at least six forward speed ratios and at least one reverse speed ratio. One of the torque transmitting mechanisms may be eliminated to provide at least five forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

[0001] The present invention relates to a family of power transmissionshaving two input clutches which selectively connect an input shaft tofirst and second pairs of planetary gear sets to provide at least fiveforward speed ratios and one reverse speed ratio.

BACKGROUND OF THE INVENTION

[0002] Passenger vehicles include a powertrain that is comprised of anengine, multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times.

[0003] A primary focus of transmission and engine design work is in thearea of increasing vehicle fuel efficiency. Manual transmissionstypically provide improved vehicle fuel economy over automatictransmissions because automatic transmissions use a torque converter forvehicle launch and multiple plate hydraulically-applied clutches forgear engagement. Clutches of this type, left unengaged or idling, imposea parasitic drag torque on a drive line due to the viscous shearingaction which exists between the plates and discs rotating at differentspeeds relative to one another. This drag torque adversely affectsvehicle fuel economy for automatic transmissions. Also, the hydraulicpump that generates the pressure needed for operating theabove-described clutches further reduces fuel efficiency associated withautomatic transmissions. Manual transmissions eliminate these problems.

[0004] While manual transmissions are not subject to the above describedfuel efficiency related problems, manual transmissions typically providepoor shift quality because a significant torque interruption is requiredduring each gear shift as the engine is disengaged from the transmissionby the clutch to allow shafts rotating at different speeds to besynchronized.

[0005] So called “automated manual” transmissions provide electronicshifting in a manual transmission configuration which, in certaincircumstances, improves fuel efficiency by eliminating the parasiticlosses associated with the torque converter and hydraulic pump neededfor clutching. Like manual transmissions, a drawback of automated manualtransmissions is that the shift quality is not as high as an automatictransmission because of the torque interruption during shifting.

[0006] So called “dual-clutch automatic” transmissions also eliminatethe torque converter and replace hydraulic clutches with synchronizersbut they go further to provide gear shift quality which is superior tothe automated manual transmission and similar to the conventionalautomatic transmission, which makes them quite attractive. However, mostknown dual-clutch automatic transmissions include a lay shaft orcountershaft gear arrangement, and have not been widely applied invehicles because of their complexity, size and cost. For example, a dualclutch lay shaft transmission could require eight sets of gears, twoinput/shift clutches and seven synchronizers/dog clutches to provide sixforward speed ratios and a reverse speed ratio. An example of adual-clutch automatic transmission is described in U.S. Pat. No.5,385,064, which is hereby incorporated by reference.

SUMMARY OF THE INVENTION

[0007] The invention provides a low content multi-speed dual-clutchtransmission family utilizing planetary gear sets rather than lay shaftgear arrangements. In particular, the invention includes four planetarygear sets, two input/shift clutches, and eight selectable torquetransmitting mechanisms to provide at least six forward speed ratios anda reverse speed ratio.

[0008] According to one aspect of the invention, the family oftransmissions has four planetary gear sets, each of which includes afirst, second and third member, which members may comprise a sun gear,ring gear, or a planet carrier assembly member.

[0009] In referring to the first, second, third and fourth gear sets inthis description and in the claims, these sets may be counted “first” to“fourth” in any order in the drawings (i.e. left-to-right,right-to-left, etc.).

[0010] In another aspect of the present invention, each of the planetarygear sets may be of the single pinion type or of the double pinion type.

[0011] In yet another aspect of the present invention, the first memberof the first planetary gear set is continuously connected with the firstmember of the second planetary gear set through a first interconnectingmember.

[0012] In yet another aspect of the present invention, another member ofthe first or second planetary gear set is continuously connected withthe first member of the third planetary gear set and with the outputshaft through a second interconnecting member.

[0013] In yet another aspect of the present invention, the second memberof the third planetary gear set is continuously connected with the firstmember of the fourth planetary gear set through a third interconnectingmember.

[0014] In accordance with a further aspect of the invention, a firstinput clutch selectively connects the input shaft with a member of thefirst or second planetary gear set.

[0015] In accordance with another aspect of the present invention, asecond input clutch selectively connects the input shaft with the thirdmember of the third planetary gear set.

[0016] In another aspect of the invention, first and second torquetransmitting mechanisms, such as synchronizers, selectively connectmembers of the first or second planetary gear sets with other members ofthe first or second planetary gear sets, or with the first input clutch.

[0017] In still a further aspect of the invention, third and fourthtorque transmitting mechanisms, such as synchronizers, selectivelyconnect members of the third planetary gear set with members of thefourth planetary gear set.

[0018] In still another aspect of the invention, fifth and sixth torquetransmitting mechanisms, such as braking synchronizers, selectivelyconnect members of the first or second planetary gear set with thestationary member.

[0019] In still another aspect of the invention, seventh and eighthtorque transmitting mechanisms, such as braking synchronizers,selectively connect members of the fourth planetary gear set with thestationary member.

[0020] In accordance with a further aspect of the invention, the inputclutches and torque transmitting mechanisms are selectively engaged incombinations of at least three to provide at least six forward speedratios and a reverse speed ratio.

[0021] In accordance with a further aspect of the invention, the firstinput clutch is applied for odd number speed ranges, and the secondinput clutch is applied for even number speed ranges, or vice versa.

[0022] In another aspect of the invention, the first input clutch andthe second input clutch are interchanged (i.e. alternately engaged) toshift from odd number speed range to even number speed range, or viceversa.

[0023] In accordance with a further aspect of the invention, eachselected torque transmitting mechanism for a new speed ratio is engagedprior to shifting of the input clutches to achieve shifts without torqueinterruptions.

[0024] In accordance with a further aspect of the invention, at leastone pair of synchronizers is executed as a double synchronizer to reducecost and package size.

[0025] In accordance with a further aspect of the invention, at leastone of the torque transmitting mechanisms can be eliminated to realizefive forward speed ratios and a reverse speed ratio.

[0026] The above objects, features, advantages, and other objects,features, and advantages of the present invention are readily apparentfrom the following detailed description of the best modes for carryingout the invention when taken in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

[0028]FIG. 1b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1a;

[0029]FIG. 2a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0030]FIG. 2b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2a;

[0031]FIG. 3a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0032]FIG. 3b a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3a;

[0033]FIG. 4a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0034]FIG. 4b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4a;

[0035]FIG. 5a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0036]FIG. 5b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5a;

[0037]FIG. 6a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0038]FIG. 6b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6a;

[0039]FIG. 7a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0040]FIG. 7b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7a;

[0041]FIG. 8a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0042]FIG. 8b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8a;

[0043]FIG. 9a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0044]FIG. 9b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9a;

[0045]FIG. 10a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0046]FIG. 10b is a truth table and chart depicting some of theoperating characteristics of the powertrain shown in FIG. 10a;

[0047]FIG. 11a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0048]FIG. 11b is a truth table and chart depicting some of theoperating characteristics of the powertrain shown in FIG. 11a;

[0049]FIG. 12a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0050]FIG. 12b is a truth table and chart depicting some of theoperating characteristics of the powertrain shown in FIG. 12a;

[0051]FIG. 13a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

[0052]FIG. 13b is a truth table and chart depicting some of theoperating characteristics of the powertrain shown in FIG. 13a;

[0053]FIG. 14a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

[0054]FIG. 14b is a truth table and chart depicting some of theoperating characteristics of the powertrain shown in FIG. 14a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] Referring to the drawings, wherein like characters represent thesame or corresponding parts throughout the several views, there is shownin FIG. 1a a powertrain 10 having a conventional engine 12, a planetarytransmission 14, and a conventional final drive mechanism 16.

[0056] The planetary transmission 14 includes an input shaft 17continuously connected with the engine 12, a planetary gear arrangement18, and an output shaft 19 continuously connected with the final drivemechanism 16. The planetary gear arrangement 18 includes four planetarygear sets 20, 30, 40 and 50.

[0057] The planetary gear set 20 includes a sun gear member 22, a ringgear member 24, and a planet carrier assembly member 26. The planetcarrier assembly member 26 includes a plurality of pinion gears 27rotatably mounted on a carrier member 29 and disposed in meshingrelationship with both the sun gear member 22 and the ring gear member24.

[0058] The planetary gear set 30 includes a sun gear member 32, a ringgear member 34, and a planet carrier assembly member 36. The planetcarrier assembly member 36 includes a plurality of pinion gears 37rotatably mounted on a carrier member 39 and disposed in meshingrelationship with both the sun gear member 32 and the ring gear member34.

[0059] The planetary gear set 40 includes a sun gear member 42, a ringgear member 44, and a planet carrier assembly member 46. The planetcarrier assembly member 46 includes a plurality of pinion gears 47rotatably mounted on a carrier member 49 and disposed in meshingrelationship with both the sun gear member 42 and the ring gear member44.

[0060] The planetary gear set 50 includes a sun gear member 52, a ringgear member 54, and a planet carrier assembly member 56. The planetcarrier assembly member 56 includes a plurality of pinion gears 57rotatably mounted on a carrier member 59 and disposed in meshingrelationship with both the sun gear member 52 and the ring gear member54.

[0061] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 20, 30, 40 and 50 are divided into first andsecond transmission subsets 60, 61 which are alternatively engaged toprovide odd number and even number speed ranges, respectively.Transmission subset 60 includes planetary gear sets 20 and 30, andtransmission subset 61 includes planetary gear sets 40 and 50. Theoutput shaft 19 is continuously connected with members of both subsets60 and 61.

[0062] As mentioned above, the first and second input clutches 62, 63are alternatively engaged for transmitting power from the input shaft 17to transmission subset 60 or transmission subset 61. The first andsecond input clutches 62, 63 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 60, 61 prior to engaging therespective input clutches 62, 63. The preselection is achieved by meansof electronically controlled synchronizers. As shown, the planetary geararrangement includes eight torque transmitting mechanisms 64, 65, 66,67, 68, 69, 70 and 71. The torque transmitting mechanisms 64, 65, 68 and69 comprise braking synchronizers, and the torque transmittingmechanisms 66, 67, 70 and 71 comprise rotating synchronizers.

[0063] The braking synchronizers and rotating synchronizers arereferenced in the claims as follows: first and second torquetransmitting mechanisms 66, 67; third and fourth torque transmittingmechanisms 70, 71; fifth and sixth torque transmitting mechanisms 64,65; and seventh and eighth torque transmitting mechanisms 68, 69. Otherfamily members are similarly referenced in the claims (i.e. rotatingsynchronizers generally in order of planetary gear sets from left toright in Figures, and braking synchronizers generally in order ofplanetary gear sets from left to right in Figures).

[0064] By way of example, synchronizers which may be implemented as therotating and/or braking synchronizers referenced herein are shown in thefollowing patents, each of which are incorporated by reference in theirentirety: U.S. Pat. Nos. 5,651,435; 5,975,263; 5,560,461; 5,641,045;5,497,867; 6,354,416.

[0065] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 60, 61 (i.e. through the clutch 62to the sun gear member 32 and through the clutch 63 to the sun gearmember 42). The planet carrier assembly member 26 is continuouslyconnected with the ring gear member 34 through the interconnectingmember 72. The planet carrier assembly member 46 is continuouslyconnected with the ring gear member 24 and the output shaft 19 throughthe interconnecting member 74. The ring gear member 44 is continuouslyconnected with the sun gear member 52 through the interconnecting member76.

[0066] The planet carrier assembly member 26 is selectively connectablewith the transmission housing 80 through the braking synchronizer 64.The sun gear member 22 is selectively connectable with the transmissionhousing 80 through the braking synchronizer 65. The planet carrierassembly member 36 is selectively connectable with the sun gear member32 through the synchronizer 66. The ring gear member 24 is selectivelyconnectable with the planet carrier assembly member 36 through thesynchronizer 67. The ring gear member 54 is selectively connectable withthe transmission housing 80 through the braking synchronizer 68. Theplanet carrier assembly member 56 is selectively connectable with thetransmission housing 80 through the braking synchronizer 69. The planetcarrier assembly member 46 is selectively connectable with the ring gearmember 54 through the synchronizer 70. The planet carrier assemblymember 46 is selectively connectable with the planet carrier assemblymember 56 through the synchronizer 71.

[0067] As shown in FIG. 1b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

[0068] The reverse speed ratio is established with the engagement of theinput clutch 63, the braking synchronizer 68 and the synchronizer 71.The input clutch 63 connects the sun gear member 42 to the input shaft17. The braking synchronizer 68 connects the ring gear member 54 to thetransmission housing 80. The synchronizer 71 connects the planet carrierassembly member 46 to the planet carrier assembly member 56. The sungear member 42 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 46 and the planet carrier assembly member56 rotate at the same speed as the output shaft 19. The ring gear member44 rotates at the same speed as the sun gear member 52. The planetcarrier assembly member 46, and therefore the output shaft 19, rotatesat a speed determined from the speed of the ring gear member 44, thespeed of the sun gear member 42 and the ring gear/sun gear tooth ratioof the planetary gear set 40. The ring gear member 54 does not rotate.The planet carrier assembly member 56 rotates at a speed determined fromthe speed of the sun gear member 52 and the ring gear/sun gear toothratio of the planetary gear set 50. The numerical value of the reversespeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 40, 50.

[0069] The first forward speed ratio is established with the engagementof the input clutch 63, the braking synchronizer 69 and the synchronizer70. The input clutch 63 connects the sun gear member 42 to the inputshaft 17. The braking synchronizer 69 connects the planet carrierassembly member 56 to the transmission housing 80. The synchronizer 70connects the planet carrier assembly member 46 to the ring gear member54. The sun gear member 42 rotates at the same speed as the input shaft17. The planet carrier assembly member 46 and the ring gear member 54rotate at the same speed as the output shaft 19. The ring gear member 44rotates at the same speed as the sun gear member 52. The planet carrierassembly member 46, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 44, the speed ofthe sun gear member 42 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The planet carrier assembly member 56 does notrotate. The ring gear member 54 rotates at a speed determined from thespeed of the sun gear member 52 and the ring gear/sun gear tooth ratioof the planetary gear set 50. The numerical value of the first forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 40, 50.

[0070] The second forward speed ratio is established with the engagementof the input clutch 62, the braking synchronizer 64 and the synchronizer67. The input clutch 62 connects the sun gear member 32 to the inputshaft 17. The braking synchronizer 64 connects the planet carrierassembly member 26 to the transmission housing 80. The synchronizer 67connects the ring gear member 24 to the planet carrier assembly member36. The planet carrier assembly member 26 and the ring gear member 34 donot rotate. The ring gear member 24 and the planet carrier assemblymembers 36, 46 rotate at the same speed as the output shaft 19. The sungear member 32 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 36, and therefore the output shaft 19,rotates at a speed determined from the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set30.

[0071] The third forward speed ratio is established with the engagementof the input clutch 63 and the braking synchronizers 68, 69. The inputclutch 63 connects the sun gear member 42 to the input shaft 17. Thebraking synchronizer 68 connects the ring gear member 54 to thetransmission housing 80. The braking synchronizer 69 connects the planetcarrier assembly member 56 to the transmission housing 80. The sun gearmember 42 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 46 rotates at the same speed as the output shaft19. The ring gear member 44 and the planetary gear set 50 do not rotate.The planet carrier assembly member 46, and therefore the output shaft19, rotates at a speed determined from the speed of the sun gear member42 and the ring gear/sun gear tooth ratio of the planetary gear set 40.The numerical value of the third forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set40.

[0072] The fourth forward speed ratio is established with the engagementof the input clutch 62, the braking synchronizer 65 and the synchronizer67. The input clutch 62 connects the sun gear member 32 to the inputshaft 17. The braking synchronizer 65 connects the sun gear member 22 tothe transmission housing 80. The synchronizer 67 connects the ring gearmember 24 to the planet carrier assembly member 36. The sun gear member22 does not rotate. The planet carrier assembly member 26 rotates at thesame speed as the ring gear member 34. The ring gear member 24, theplanet carrier assembly member 36 and the planet carrier assembly member46 rotates at the same speed as the output shaft 19. The ring gearmember 24, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 26 andthe ring gear/sun gear tooth ratio of the planetary gear set 20. The sungear member 32 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 36 rotates at a speed determined from thespeed of the ring gear member 34, the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thenumerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets20, 30.

[0073] The fifth forward speed ratio is established with the engagementof the input clutch 63, and the synchronizers 70, 71. In thisconfiguration, the input shaft 17 is directly connected to the outputshaft 19. The numerical value of the fifth forward speed ratio is 1.

[0074] The sixth forward speed ratio is established with the engagementof the input clutch 62, the braking synchronizer 65 and the synchronizer66. The input clutch 62 connects the sun gear member 32 to the inputshaft 17. The braking synchronizer 65 connects the sun gear member 22 tothe transmission housing 80. The synchronizer 66 connects the planetcarrier assembly member 36 to the sun gear member 32. The sun gearmember 22 does not rotate. The planet carrier assembly member 26 and theplanetary gear set 30 rotate at the same speed as the input shaft 17.The ring gear member 24 and the planet carrier assembly member 46 rotateat the same speed as the output shaft 19. The ring gear member 24, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 26 and the ring gear/sungear tooth ratio of the planetary gear set 20. The numerical value ofthe sixth forward speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 20.

[0075] As set forth above, the engagement schedule for the torquetransmitting mechanisms is shown in the truth table of FIG. 1b. Thistruth table also provides an example of speed ratios that are availableutilizing the ring gear/sun gear tooth ratios given by way of example inFIG. 1b. The R1/S1 value is the tooth ratio of the planetary gear set20; the R2/S2 value is the tooth ratio of the planetary gear set 30; theR3/S3 value is the tooth ratio of the planetary gear set 40; and theR4/S4 value is the tooth ratio of the planetary gear set 50. Also, thechart of FIG. 1b describes the ratio steps that are attained utilizingthe sample of tooth ratios given. For example, the step ratio betweenfirst and second forward speed ratios is 1.94, while the step ratiobetween the reverse and first forward ratio is −0.47.

[0076]FIG. 2a shows a powertrain 110 having a conventional engine 12, aplanetary transmission 114, and a conventional final drive mechanism 16.The planetary transmission 114 includes an input shaft 17 connected withthe engine 12, a planetary gear arrangement 118, and an output shaft 19connected with the final drive mechanism 16. The planetary geararrangement 118 includes four planetary gear sets 120, 130, 140 and 150.

[0077] The planetary gear set 120 includes a sun gear member 122, a ringgear member 124, and a planet carrier assembly member 126. The planetcarrier assembly member 126 includes a plurality of pinion gears 127rotatably mounted on a carrier member 129 and disposed in meshingrelationship with both the sun gear member 122 and the ring gear member124.

[0078] The planetary gear set 130 includes a sun gear member 132, a ringgear member 134, and a planet carrier assembly member 136. The planetcarrier assembly member 136 includes a plurality of pinion gears 137rotatably mounted on a carrier member 139 and disposed in meshingrelationship with both the sun gear member 132 and the ring gear member134.

[0079] The planetary gear set 140 includes a sun gear member 142, a ringgear member 144, and a planet carrier assembly member 146. The planetcarrier assembly member 146 includes a plurality of pinion gears 147rotatably mounted on a carrier member 149 and disposed in meshingrelationship with both the sun gear member 142 and the ring gear member144.

[0080] The planetary gear set 150 includes a sun gear member 152, a ringgear member 154, and a planet carrier assembly member 156. The planetcarrier assembly member 156 includes a plurality of intermeshing piniongears 157, 158 rotatably mounted on a carrier member 159 and disposed inmeshing relationship with the ring gear member 154 and the sun gearmember 152, respectively.

[0081] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 120, 130, 140 and 150 are divided into firstand second transmission subsets 160, 161 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 160 includes planetary gear sets 120 and 130, andtransmission subset 161 includes planetary gear sets 140 and 150. Theoutput shaft 19 is continuously connected with members of both subsets160 and 161.

[0082] As mentioned above, the first and second input clutches 162, 163are alternatively engaged for transmitting power from the input shaft 17to transmission subset 160 or transmission subset 161. The first andsecond input clutches 162, 163 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 160, 161 prior to engagingthe respective input clutches 162, 163. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms164, 165, 166, 167, 168, 169, 170 and 171. The torque transmittingmechanisms 164, 165, 168 and 169 comprise braking synchronizers, and thetorque transmitting mechanisms 166, 167, 170 and 171 comprise rotatingsynchronizers.

[0083] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 160, 161 (i.e. through the clutch162 to the sun gear member 132 and through the clutch 163 to the sungear member 142). The planet carrier assembly member 126 is continuouslyconnected with the ring gear member 134 through the interconnectingmember 172. The planet carrier assembly member 146 is continuouslyconnected with the ring gear member 124 and the output shaft 19 throughthe interconnecting member 174. The ring gear member 144 is continuouslyconnected with the planet carrier assembly member 156 through theinterconnecting member 176.

[0084] The planet carrier assembly member 126 is selectively connectablewith the transmission housing 180 through the braking synchronizer 164.The sun gear member 122 is selectively connectable with the transmissionhousing 180 through the braking synchronizer 165. The planet carrierassembly member 136 is selectively connectable with the sun gear member132 through the synchronizer 166. The ring gear member 124 isselectively connectable with the planet carrier assembly member 136through the synchronizer 167. The sun gear member 152 is selectivelyconnectable with the transmission housing 180 through the brakingsynchronizer 168. The ring gear member 154 is selectively connectablewith the transmission housing 180 through the braking synchronizer 169.The planet carrier assembly member 146 is selectively connectable withthe sun gear member 152 through the synchronizer 170. The planet carrierassembly member 146 is selectively connectable with the ring gear member154 through the synchronizer 171.

[0085] As shown in FIG. 2b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

[0086] The reverse speed ratio is established with the engagement of theinput clutch 163, the braking synchronizer 168 and the synchronizer 171.The input clutch 163 connects the sun gear member 142 to the input shaft17. The braking synchronizer 168 connects the sun gear member 152 to thetransmission housing 180. The synchronizer 171 connects the planetcarrier assembly member 146 to the ring gear member 154. The sun gearmember 142 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 146 and the ring gear member 154 rotate at thesame speed as the output shaft 19. The ring gear member 144 rotates atthe same speed as the planet carrier assembly member 156. The planetcarrier assembly member 146, and therefore the output shaft 19, rotatesat a speed determined from the speed of the ring gear member 144, thespeed of the sun gear member 142 and the ring gear/sun gear tooth ratioof the planetary gear set 140. The sun gear member 152 does not rotate.The planet carrier assembly member 156 rotates at a speed determinedfrom the speed of the ring gear member 154 and the ring gear/sun geartooth ratio of the planetary gear set 150. The numerical value of thereverse speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 140, 150.

[0087] The first forward speed ratio is established with the engagementof the input clutch 163, the braking synchronizer 169 and thesynchronizer 170. The input clutch 163 connects the sun gear member 142to the input shaft 17. The braking synchronizer 169 connects the ringgear member 154 to the transmission housing 180. The synchronizer 170connects the planet carrier assembly member 146 to the sun gear member152. The sun gear member 142 rotates at the same speed as the inputshaft 17. The planet carrier assembly member 146 and the sun gear member152 rotate at the same speed as the output shaft 19. The ring gearmember 144 rotates at the same speed as the planet carrier assemblymember 156. The planet carrier assembly member 146, and therefore theoutput shaft 19, rotates at a speed determined from the speed of thering gear member 144, the speed of the sun gear member 142 and the ringgear/sun gear tooth ratio of the planetary gear set 140. The ring gearmember 154 does not rotate. The planet carrier assembly member 156rotates at a speed determined from the speed of the sun gear member 152and the ring gear/sun gear tooth ratio of the planetary gear set 150.The numerical value of the first forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets140, 150.

[0088] The second forward speed ratio is established with the engagementof the input clutch 162, the braking synchronizer 164 and thesynchronizer 167. The input clutch 162 connects the sun gear member 132to the input shaft 17. The braking synchronizer 164 connects the planetcarrier assembly member 126 to the transmission housing 180. Thesynchronizer 167 connects the ring gear member 124 to the planet carrierassembly member 136. The planet carrier assembly member 126 and the ringgear member 134 do not rotate. The ring gear member 124 and the planetcarrier assembly members 136, 146 rotate at the same speed as the outputshaft 19. The sun gear member 132 rotates at the same speed as the inputshaft 17. The planet carrier assembly member 136, and therefore theoutput shaft 19, rotates at a speed determined from the speed of the sungear member 132 and the ring gear/sun gear tooth ratio of the planetarygear set 130. The numerical value of the second forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 130.

[0089] The third forward speed ratio is established with the engagementof the input clutch 163 and the braking synchronizers 168, 169. Theinput clutch 163 connects the sun gear member 142 to the input shaft 17.The braking synchronizer 168 connects the sun gear member 152 to thetransmission housing 180. The braking synchronizer 169 connects the ringgear member 154 to the transmission housing 180. The sun gear member 142rotates at the same speed as the input shaft 17. The planet carrierassembly member 146 rotates at the same speed as the output shaft 19.The ring gear member 144 and the planetary gear set 150 do not rotate.The planet carrier assembly member 146, and therefore the output shaft19, rotates at a speed determined from the speed of the sun gear member142 and the ring gear/sun gear tooth ratio of the planetary gear set140. The numerical value of the third forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set140.

[0090] The fourth forward speed ratio is established with the engagementof the input clutch 162, the braking synchronizer 165 and thesynchronizer 167. The input clutch 162 connects the sun gear member 132to the input shaft 17. The braking synchronizer 165 connects the sungear member 122 to the transmission housing 180. The synchronizer 167connects the ring gear member 124 to the planet carrier assembly member136. The sun gear member 122 does not rotate. The planet carrierassembly member 126 rotates at the same speed as the ring gear member134. The ring gear member 124 and the planet carrier assembly members136, 146 rotate at the same speed as the output shaft 19. The ring gearmember 124, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 126 andthe ring gear/sun gear tooth ratio of the planetary gear set 120. Thesun gear member 132 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 136 rotates at a speed determined fromthe speed of the ring gear member 134, the speed of the sun gear member132 and the ring gear/sun gear tooth ratio of the planetary gear set130. The numerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets120, 130.

[0091] The fifth forward speed ratio is established with the engagementof the input clutch 163 and the synchronizers 170, 171. In thisconfiguration, the input shaft 17 is directly connected to the outputshaft 19. The numerical value of the fifth forward speed ratio is 1.

[0092] The sixth forward speed ratio is established with the engagementof the input clutch 162, the braking synchronizer 165 and thesynchronizer 166. The input clutch 162 connects the sun gear member 132to the input shaft 17. The braking synchronizer 165 connects the sungear member 122 to the transmission housing 180. The synchronizer 166connects the planet carrier assembly member 136 to the sun gear member132. The sun gear member 122 does not rotate. The planet carrierassembly member 126 and the planetary gear set 130 rotate at the samespeed as the input shaft 17. The ring gear member 124 and the planetcarrier assembly member 146 rotate at the same speed as the output shaft19. The ring gear member 124, and therefore the output shaft 19, rotatesat a speed determined from the speed of the planet carrier assemblymember 126 and the ring gear/sun gear tooth ratio of the planetary gearset 120. The numerical value of the sixth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 120.

[0093] As set forth above, the truth table of FIG. 2b describes theengagement sequence of the torque transmitting mechanisms utilized toprovide a reverse drive ratio and six forward speed ratios. The truthtable also provides an example of the ratios that can be attained withthe family members shown in FIG. 2a utilizing the sample tooth ratiosgiven in FIG. 2b. The R1/S1 value is the tooth ratio of the planetarygear set 120; the R2/S2 value is the tooth ratio of the planetary gearset 130; the R3/S3 value is the tooth ratio of the planetary gear set140; and the R4/S4 value is the tooth ratio of the planetary gear set150. Also shown in FIG. 2b are the ratio steps between single stepratios in the forward direction as well as the reverse to first ratiostep. For example, the first to second step ratio is 1.60.

[0094] Turning the FIG. 3a, a powertrain 210 having a conventionalengine 12, a planetary transmission 214, and conventional final drivemechanism 16 is shown.

[0095] The planetary transmission 214 includes an input shaft 17continuously connected with the engine 12, a planetary gear arrangement218, and an output shaft 19 continuously connected with the final drivemechanism 16. The planetary gear arrangement 218 includes four planetarygear sets 220, 230, 240 and 250.

[0096] The planetary gear set 220 includes a sun gear member 222, a ringgear member 224, and a planet carrier assembly member 226. The planetcarrier assembly member 226 includes a plurality of intermeshing piniongears 227, 228 rotatably mounted on a carrier member 229 and disposed inmeshing relationship with the ring gear member 224 and the sun gearmember 222, respectively.

[0097] The planetary gear set 230 includes a sun gear member 232, a ringgear member 234, and a planet carrier assembly member 236. The planetcarrier assembly member 236 includes a plurality of pinion gears 237rotatably mounted on a carrier member 239 and disposed in meshingrelationship with both the sun gear member 232 and the ring gear member234.

[0098] The planetary gear set 240 includes a sun gear member 242, a ringgear member 244, and a planet carrier assembly member 246. The planetcarrier assembly member 246 includes a plurality of pinion gears 247rotatably mounted on a carrier member 249 and disposed in meshingrelationship with both the sun gear member 242 and the ring gear member244.

[0099] The planetary gear set 250 includes a sun gear member 252, a ringgear member 254, and a planet carrier assembly member 256. The planetcarrier assembly member 256 includes a plurality of pinion gears 257rotatably mounted on a carrier member 259 and disposed in meshingrelationship with both the sun gear member 252 and the ring gear member254.

[0100] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 220, 230, 240 and 250 are divided into firstand second transmission subsets 260, 261 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 260 includes planetary gear sets 220 and 230, andtransmission subset 261 includes planetary gear sets 240 and 250. Theoutput shaft 19 is continuously connected with members of both subsets260 and 261.

[0101] As mentioned above, the first and second input clutches 262, 263are alternatively engaged for transmitting power from the input shaft 17to transmission subset 260 or transmission subset 261. The first andsecond input clutches 262, 263 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 260, 261 prior to engagingthe respective input clutches 262, 263. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms264, 265, 266, 267, 268, 269, 270 and 271. The torque transmittingmechanisms 264, 265, 268 and 269 comprise braking synchronizers, and thetorque transmitting mechanisms 266, 267, 270 and 271 comprise rotatingsynchronizers.

[0102] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 260, 261 (i.e. through the clutch262 to the sun gear member 222 and through the clutch 263 to the sungear member 242). The planet carrier assembly member 226 is continuouslyconnected with the sun gear member 232 through the interconnectingmember 272. The planet carrier assembly member 246 is continuouslyconnected with the ring gear member 234 and the output shaft 19 throughthe interconnecting member 274. The ring gear member 244 is continuouslyconnected with the sun gear member 252 through the interconnectingmember 276.

[0103] The planet carrier assembly member 226 is selectively connectablewith the transmission housing 280 through the braking synchronizer 264.The planet carrier assembly member 236 is selectively connectable withthe transmission housing 280 through the braking synchronizer 265. Thering gear member 224 is selectively connectable with the planet carrierassembly member 236 through the synchronizer 266. The sun gear member222 is selectively connectable with the planet carrier assembly member236 through the synchronizer 267. The ring gear member 254 isselectively connectable with the transmission housing 280 through thebraking synchronizer 268. The planet carrier assembly member 256 isselectively connectable with the transmission housing 280 through thebraking synchronizer 269. The planet carrier assembly member 246 isselectively connectable with the ring gear member 254 through thesynchronizer 270. The planet carrier assembly member 246 is selectivelyconnectable with the planet carrier assembly member 256 through thesynchronizer 271.

[0104] As shown in FIG. 3b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

[0105] The reverse speed ratio is established with the engagement of theinput clutch 263, the braking synchronizer 268 and the synchronizer 271.The input clutch 263 connects the sun gear member 242 to the input shaft17. The braking synchronizer 268 connects the ring gear member 254 tothe transmission housing 280. The synchronizer 271 connects the planetcarrier assembly member 246 to the planet carrier assembly member 256.The sun gear member 242 rotates at the same speed as the input shaft 17.The planet carrier assembly member 246 and the planet carrier assemblymember 256 rotate at the same speed as the output shaft 19. The ringgear member 244 rotates at the same speed as the sun gear member 252.The planet carrier assembly member 246, and therefore the output shaft19, rotates at a speed determined from the speed of the ring gear member244, the speed of the sun gear member 242 and the ring gear/sun geartooth ratio of the planetary gear set 240. The ring gear member 254 doesnot rotate. The planet carrier assembly member 256 rotates at a speeddetermined from the speed of the sun gear member 252 and the ringgear/sun gear tooth ratio of the planetary gear set 250. The numericalvalue of the reverse speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 240, 250.

[0106] The first forward speed ratio is established with the engagementof the input clutch 263, the braking synchronizer 269 and thesynchronizer 270. The input clutch 263 connects the sun gear member 242to the input shaft 17. The braking synchronizer 269 connects the planetcarrier assembly member 256 to the transmission housing 280. Thesynchronizer 270 connects the planet carrier assembly member 246 to thering gear member 254. The sun gear member 242 rotates at the same speedas the input shaft 17. The planet carrier assembly member 246 and thering gear member 254 rotate at the same speed as the output shaft 19.The ring gear member 244 rotates at the same speed as the sun gearmember 252. The planet carrier assembly member 246, and therefore theoutput shaft 19, rotates at a speed determined from the speed of thering gear member 244, the speed of the sun gear member 242 and the ringgear/sun gear tooth ratio of the planetary gear set 240. The planetcarrier assembly member 256 does not rotate. The ring gear member 254rotates at a speed determined from the speed of the sun gear member 252and the ring gear/sun gear tooth ratio of the planetary gear set 250.The numerical value of the first forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets240, 250.

[0107] The second forward speed ratio is established with the engagementof the input clutch 262, the braking synchronizer 265 and thesynchronizer 266. The input clutch 262 connects the sun gear member 222to the input shaft 17. The braking synchronizer 265 connects the planetcarrier assembly member 236 to the transmission housing 280. Thesynchronizer 266 connects the ring gear member 224 to the planet carrierassembly member 236. The sun gear member 222 rotates at the same speedas the input shaft 17. The planet carrier assembly member 226 rotates atthe same speed as the sun gear member 232. The ring gear member 224 andthe planet carrier assembly member 236 do not rotate. The planet carrierassembly member 226 rotates at a speed determined from the speed of thesun gear member 222 and the ring gear/sun gear tooth ratio of theplanetary gear set 220. The ring gear member 234 and the planet carrierassembly member 246 rotate at the same speed as the output shaft 19. Thering gear member 234, and therefore the output shaft 19, rotates at aspeed determined from the speed of the sun gear member 232 and the ringgear/sun gear tooth ratio of the planetary gear set 230. The numericalvalue of the second forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 220, 230.

[0108] The third forward speed ratio is established with the engagementof the input clutch 263, and the braking synchronizers 268, 269. Theinput clutch 263 connects the sun gear member 242 to the input shaft 17.The braking synchronizer 268 connects the ring gear member 254 to thetransmission housing 280. The braking synchronizer 269 connects theplanet carrier assembly member 256 to the transmission housing 280. Thesun gear member 242 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 246 rotates at the same speed as theoutput shaft 19. The ring gear member 244 and the planetary gear set 250do not rotate. The planet carrier assembly member 246, and therefore theoutput shaft 19, rotates at a speed determined from the speed of the sungear member 242 and the ring gear/sun gear tooth ratio of the planetarygear set 240. The numerical value of the third forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 240.

[0109] The fourth forward speed ratio is established with the engagementof the input clutch 262, the braking synchronizer 264 and thesynchronizer 266. The input clutch 262 connects the sun gear member 222to the input shaft 17. The braking synchronizer 264 connects the planetcarrier assembly member 226 to the transmission housing 280. Thesynchronizer 266 connects the ring gear member 224 to the planet carrierassembly member 236. The sun gear member 222 rotates at the same speedas the input shaft 17. The planet carrier assembly member 226 and thesun gear member 232 do not rotate. The ring gear member 224 rotates atthe same speed as the planet carrier assembly member 236. The ring gearmember 224 rotates at a speed determined from the speed of the sun gearmember 222 and the ring gear/sun gear tooth ratio of the planetary gearset 220. The ring gear member 234 and the planet carrier assembly member246 rotate at the same speed as the output shaft 19. The ring gearmember 234, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 236 andthe ring gear/sun gear tooth ratio of the planetary gear set 230. Thenumerical value of the fourth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets220, 230.

[0110] The fifth forward speed ratio is established with the engagementof the input clutch 263 and the synchronizers 270, 271. In thisconfiguration, the input shaft 17 is directly connected to the outputshaft 19. The numerical value of the fifth forward speed ratio is 1.

[0111] The sixth forward speed ratio is established with the engagementof the input clutch 262, the braking synchronizer 264 and thesynchronizer 267. The input clutch 262 connects the sun gear member 222to the input shaft 17. The braking synchronizer 264 connects the planetcarrier assembly member 226 to the transmission housing 280. Thesynchronizer 267 connects the sun gear member 222 to the planet carrierassembly member 236. The sun gear member 222 and the planet carrierassembly member 236 rotate at the same speed as the input shaft 17. Theplanet carrier assembly member 226 and the sun gear member 232 do notrotate. The ring gear member 234 and the planet carrier assembly member246 rotate at the same speed as the output shaft 19. The ring gearmember 234, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 236 andthe ring gear/sun gear tooth ratio of the planetary gear set 230. Thenumerical value of the sixth forward speed ratio is determined utilizingthe ring gear/sun gear tooth ratio of the planetary gear set 230.

[0112] As previously set forth, the truth table of FIG. 3b describes thecombinations of engagements utilized for six forward speed ratios andone reverse speed ratio. The truth table also provides an example ofspeed ratios that are available with the family member described above.These examples of speed ratios are determined the tooth ratios given inFIG. 3b. The R1/S1 value is the tooth ratio of the planetary gear set220; the R2/S2 value is the tooth ratio of the planetary gear set 230;the R3/S3 value is the tooth ratio of the planetary gear set 240; andthe R4/S4 value is the tooth ratio of the planetary gear set 250. Alsodepicted in FIG. 3b is a chart representing the ratio steps betweenadjacent forward speed ratios and the reverse speed ratio. For example,the first to second ratio interchange has a step of 2.00.

[0113] A powertrain 310, shown in FIG. 4a, includes the engine 12, aplanetary transmission 314, and the final drive mechanism 16. Theplanetary transmission 314 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 318, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 318 includes four planetary gear sets320, 330, 340 and 350.

[0114] The planetary gear set 320 includes a sun gear member 322, a ringgear member 324, and a planet carrier assembly member 326. The planetcarrier assembly member 326 includes a plurality of intermeshing piniongears 327, 328 rotatably mounted on a carrier member 329 and disposed inmeshing relationship with the ring gear member 324 and the sun gearmember 322, respectively.

[0115] The planetary gear set 330 includes a sun gear member 332, a ringgear member 334, and a planet carrier assembly member 336. The planetcarrier assembly member 336 includes a plurality of pinion gears 337rotatably mounted on a carrier member 339 and disposed in meshingrelationship with both the sun gear member 332 and the ring gear member334.

[0116] The planetary gear set 340 includes a sun gear member 342, a ringgear member 344, and a planet carrier assembly member 346. The planetcarrier assembly member 346 includes a plurality of pinion gears 347rotatably mounted on a carrier member 349 and disposed in meshingrelationship with both the sun gear member 342 and the ring gear member344.

[0117] The planetary gear set 350 includes a sun gear member 352, a ringgear member 354, and a planet carrier assembly member 356. The planetcarrier assembly member 356 includes a plurality of pinion gears 357rotatably mounted on a carrier member 359 and disposed in meshingrelationship with both the sun gear member 352 and the ring gear member354.

[0118] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 320, 330, 340 and 350 are divided into firstand second transmission subsets 360, 361 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 360 includes planetary gear sets 320 and 330, andtransmission subset 361 includes planetary gear sets 340 and 350. Theoutput shaft 19 is continuously connected with members of both subsets360 and 361.

[0119] As mentioned above, the first and second input clutches 362, 363are alternatively engaged for transmitting power from the input shaft 17to transmission subset 360 or transmission subset 361. The first andsecond input clutches 362, 363 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 360, 361 prior to engagingthe respective input clutches 362, 363. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms364, 365, 366, 367, 368, 369, 370 and 371. The torque transmittingmechanisms 364, 365, 368 and 369 comprise braking synchronizers, and thetorque transmitting mechanisms 366, 367, 370 and 371 comprise rotatingsynchronizers.

[0120] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 360, 361 (i.e. through the clutch362 to the sun gear member 322 and through the clutch 363 to the sungear member 342). The planet carrier assembly member 326 is continuouslyconnected with the sun gear member 332 through the interconnectingmember 372. The planet carrier assembly member 346 is continuouslyconnected with the ring gear member 334 and the output shaft 19 throughthe interconnecting member 374. The ring gear member 344 is continuouslyconnected with the sun gear member 352 through the interconnectingmember 376.

[0121] The planet carrier assembly member 326 is selectively connectablewith the transmission housing 380 through the braking synchronizer 364.The planet carrier assembly member 336 is selectively connectable withthe transmission housing 380 through the braking synchronizer 365. Thering gear member 324 is selectively connectable with the planet carrierassembly member 336 through the synchronizer 366. The sun gear member322 is selectively connectable with the planet carrier assembly member336 through the synchronizer 367. The ring gear member 354 isselectively connectable with the transmission housing 380 through thebraking synchronizer 368. The planet carrier assembly member 356 isselectively connectable with the transmission housing 380 through thebraking synchronizer 369. The planet carrier assembly member 346 isselectively connectable with the ring gear member 354 through thesynchronizer 370. The planet carrier assembly member 346 is selectivelyconnectable with the planet carrier assembly member 356 through thesynchronizer 371.

[0122] The truth tables given in FIGS. 4b, 5 b, 6 b, 7 b, 8 b, 9 b, 10b, 11 b, 12 b, 13 b and 14 b show the engagement sequences for thetorque transmitting mechanisms to provide at least five forward speedratios and one reverse speed ratio. As shown and described above for theconfigurations in FIGS. 1a, 2 a and 3 a, those skilled in the art willunderstand from the respective truth tables how the speed ratios areestablished through the planetary gear sets identified in the writtendescription.

[0123] The truth table shown in FIG. 4b describes the engagementcombination and engagement sequence necessary to provide the reversedrive ratio and six forward speed ratios. A sample of the numericalvalues for the ratios is also provided in the truth table of FIG. 4b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 4b. The R1/S1 value is the tooth ratio for theplanetary gear set 320; the R2/S2 value is the tooth ratio for theplanetary gear set 330; the R3/S3 value is the tooth ratio for theplanetary gear set 340; and the R4/S4 value is the tooth ratio for theplanetary gear set 350. Also given in FIG. 4b is a chart describing thestep ratios between the adjacent forward speed ratios and the reverse tofirst forward speed ratio. For example, the first to second forwardspeed ratio step is 2.00.

[0124] Those skilled in the art will recognize that the numerical valuesof the reverse and first forward speed ratios are determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 340, 350.The numerical values of the second and fourth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 320, 330. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 340. The numerical value of the fifth forwardspeed ratio is 1. The numerical value of the sixth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 330.

[0125] A powertrain 410 shown in FIG. 5a includes a conventional engine12, a planetary transmission 414, and a conventional final drivemechanism 16. The planetary transmission 414 includes an input shaft 17connected with the engine 12, a planetary gear arrangement 418, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 418 includes four planetary gear sets420, 430, 440 and 450.

[0126] The planetary gear set 420 includes a sun gear member 422, a ringgear member 424, and a planet carrier assembly member 426. The planetcarrier assembly member 426 includes a plurality of intermeshing piniongears 427, 428 rotatably mounted on a carrier member 429 and disposed inmeshing relationship with the ring gear member 424 and the sun gearmember 422, respectively.

[0127] The planetary gear set 430 includes a sun gear member 432, a ringgear member 434, and a planet carrier assembly member 436. The planetcarrier assembly member 436 includes a plurality of pinion gears 437rotatably mounted on a carrier member 439 and disposed in meshingrelationship with both the sun gear member 432 and the ring gear member434.

[0128] The planetary gear set 440 includes a sun gear member 442, a ringgear member 444, and a planet carrier assembly member 446. The planetcarrier assembly member 446 includes a plurality of pinion gears 447rotatably mounted on a carrier member 449 and disposed in meshingrelationship with both the sun gear member 442 and the ring gear member444.

[0129] The planetary gear set 450 includes a sun gear member 452, a ringgear member 454, and a planet carrier assembly member 456. The planetcarrier assembly member 456 includes a plurality of pinion gears 457rotatably mounted on a carrier member 459 and disposed in meshingrelationship with both the sun gear member 452 and the ring gear member454.

[0130] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 420, 430, 440 and 450 are divided into firstand second transmission subsets 460, 461 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 460 includes planetary gear sets 420 and 430, andtransmission subset 461 includes planetary gear sets 440 and 450. Theoutput shaft 19 is continuously connected with members of both subsets460 and 461.

[0131] As mentioned above, the first and second input clutches 462, 463are alternatively engaged for transmitting power from the input shaft 17to transmission subset 460 or transmission subset 461. The first andsecond input clutches 462, 463 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 460, 461 prior to engagingthe respective input clutches 462, 463. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms464, 465, 466, 467, 468, 469, 470 and 471. The torque transmittingmechanisms 464, 465, 468 and 469 comprise braking synchronizers, and thetorque transmitting mechanisms 466, 467, 470 and 471 comprise rotatingsynchronizers.

[0132] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 460, 461 (i.e. through the clutch462 to the sun gear member 422 and through the clutch 463 to the sungear member 442). The planet carrier assembly member 426 is continuouslyconnected with the sun gear member 432 through the interconnectingmember 472. The planet carrier assembly member 446 is continuouslyconnected with the ring gear member 434 and the output shaft 19 throughthe interconnecting member 474. The ring gear member 444 is continuouslyconnected with the sun gear member 452 through the interconnectingmember 476.

[0133] The planet carrier assembly member 426 is selectively connectablewith the transmission housing 480 through the braking synchronizer 464.The ring gear member 424 is selectively connectable with thetransmission housing 480 through the braking synchronizer 465. The sungear member 422 is selectively connectable with the planet carrierassembly member 436 through the synchronizer 466. The ring gear member424 is selectively connectable with the planet carrier assembly member436 through the synchronizer 467. The ring gear member 454 isselectively connectable with the transmission housing 480 through thebraking synchronizer 468. The planet carrier assembly member 456 isselectively connectable with the transmission housing 480 through thebraking synchronizer 469. The planet carrier assembly member 446 isselectively connectable with the ring gear member 454 through thesynchronizer 470. The planet carrier assembly member 446 is selectivelyconnectable with the planet carrier assembly member 456 through thesynchronizer 471.

[0134] As shown in FIG. 5b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio.

[0135]FIG. 5b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first ratio. For example, theratio step between the first and second forward ratios is 2.00. Thoseskilled in the art will recognize that the numerical values of thereverse and first forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 440, 450. Thenumerical values of the second and fourth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 420, 430. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 440. The numerical value of the fifth forwardspeed ratio is 1. The numerical value of the sixth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 430.

[0136] A powertrain 510, shown in FIG. 6a, includes a conventionalengine 12, a powertrain 514, and a conventional final drive mechanism16. The powertrain 514 includes an input shaft 17 connected with theengine 12, a planetary gear arrangement 518, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 518 includes four planetary gear sets 520, 530, 540 and550.

[0137] The planetary gear set 520 includes a sun gear member 522, a ringgear member 524, and a planet carrier assembly member 526. The planetcarrier assembly member 526 includes a plurality of pinion gears 527rotatably mounted on a carrier member 529 and disposed in meshingrelationship with both the sun gear member 522 and the ring gear member524.

[0138] The planetary gear set 530 includes a sun gear member 532, a ringgear member 534, and a planet carrier assembly member 536. The planetcarrier assembly member 536 includes a plurality of pinion gears 537rotatably mounted on a carrier member 539 and disposed in meshingrelationship with both the sun gear member 532 and the ring gear member534.

[0139] The planetary gear set 540 includes a sun gear member 542, a ringgear member 544, and a planet carrier assembly member 546. The planetcarrier assembly member 546 includes a plurality of intermeshing piniongears 547, 548 rotatably mounted on a carrier member 549 and disposed inmeshing relationship with the ring gear member 544 and the sun gearmember 542, respectively.

[0140] The planetary gear set 550 includes a sun gear member 552, a ringgear member 554, and a planet carrier assembly member 556. The planetcarrier assembly member 556 includes a plurality of pinion gears 557rotatably mounted on a carrier member 559 and disposed in meshingrelationship with both the sun gear member 552 and the ring gear member554.

[0141] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 520, 530, 540 and 550 are divided into firstand second transmission subsets 560, 561 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 560 includes planetary gear sets 520 and 530, andtransmission subset 561 includes planetary gear sets 540 and 550. Theoutput shaft 19 is continuously connected with members of both subsets560 and 561.

[0142] As mentioned above, the first and second input clutches 562, 563are alternatively engaged for transmitting power from the input shaft 17to transmission subset 560 or transmission subset 561. The first andsecond input clutches 562, 563 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 560, 561 prior to engagingthe respective input clutches 562, 563. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms564, 565, 566, 567, 568, 569, 570 and 571. The torque transmittingmechanisms 564, 565, 568 and 569 comprise braking synchronizers, and thetorque transmitting mechanisms 566, 567, 570 and 571 comprise rotatingsynchronizers.

[0143] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 560, 561 (i.e. through the clutch562 to the sun gear member 522 and through the clutch 563 to the ringgear member 544). The ring gear member 524 is continuously connectedwith the sun gear member 532 through the interconnecting member 572. Theplanet carrier assembly member 546 is continuously connected with thering gear member 534 and the output shaft 19 through the interconnectingmember 574. The sun gear member 542 is continuously connected with thesun gear member 552 through the interconnecting member 576.

[0144] The ring gear member 524 is selectively connectable with thetransmission housing 580 through the braking synchronizer 564. Theplanet carrier assembly member 526 is selectively connectable with thetransmission housing 580 through the braking synchronizer 565. Theplanet carrier assembly member 526 is selectively connectable with theplanet carrier assembly member 536 through the synchronizer 566. The sungear member 522 is selectively connectable with the planet carrierassembly member 536 through the synchronizer 567. The ring gear member554 is selectively connectable with the transmission housing 580 throughthe braking synchronizer 568. The planet carrier assembly member 556 isselectively connectable with the transmission housing 580 through thebraking synchronizer 569. The planet carrier assembly member 546 isselectively connectable with the ring gear member 554 through thesynchronizer 570. The planet carrier assembly member 546 is selectivelyconnectable with the planet carrier assembly member 556 through thesynchronizer 571.

[0145] As shown in FIG. 6b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The chart of FIG. 6b describesthe ratio steps between adjacent forward speed ratios and the ratio stepbetween the reverse and first forward speed ratio.

[0146] Those skilled in the art, upon reviewing the truth table and theschematic representation of FIG. 6a can determine that the numericalvalues of the reverse and first forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets540, 550. The numerical values of the second and sixth forward speedratios are determined utilizing the ring gear/sun gear tooth ratios ofthe planetary gear sets 520, 530. The numerical value of the thirdforward speed ratio is 1. The numerical value of the fourth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 530. The numerical value of the fifth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 540.

[0147] The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6b. R1/S1 value isthe tooth ratio of the planetary gear set 520; the R2/S2 value is thetooth ratio of the planetary gear set 530; the R3/S3 value is the toothratio of the planetary gear set 540; and the R4/S4 value is the toothratio of the planetary gear set 550.

[0148] A powertrain 610, shown in FIG. 7a, has the engine and torqueconverter 12, a planetary transmission 614, and the final drivemechanism 16. The planetary transmission 614 includes the input shaft17, a planetary gear arrangement 618, and the output shaft 19. Theplanetary gear arrangement 618 includes four planetary gear sets 620,630, 640 and 650.

[0149] The planetary gear set 620 includes a sun gear member 622, a ringgear member 624, and a planet carrier assembly member 626. The planetcarrier assembly member 626 includes a plurality of intermeshing piniongears 627, 628 rotatably mounted on a carrier member 629 and disposed inmeshing relationship with the ring gear member 624 and the sun gearmember 622, respectively.

[0150] The planetary gear set 630 includes a sun gear member 632, a ringgear member 634, and a planet carrier assembly member 636. The planetcarrier assembly member 636 includes a plurality of pinion gears 637rotatably mounted on a carrier member 639 and disposed in meshingrelationship with both the sun gear member 632 and the ring gear member634.

[0151] The planetary gear set 640 includes a sun gear member 642, a ringgear member 644, and a planet carrier assembly member 646. The planetcarrier assembly member 646 includes a plurality of pinion gears 647rotatably mounted on a carrier member 649 and disposed in meshingrelationship with both the sun gear member 642 and the ring gear member644.

[0152] The planetary gear set 650 includes a sun gear member 652, a ringgear member 654, and a planet carrier assembly member 656. The planetcarrier assembly member 656 includes a plurality of intermeshing piniongears 657, 658 rotatably mounted on a carrier member 659 and disposed inmeshing relationship with the ring gear member 654 and the sun gearmember 652, respectively.

[0153] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 620, 630, 640 and 650 are divided into firstand second transmission subsets 660, 661 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 660 includes planetary gear sets 620 and 630, andtransmission subset 661 includes planetary gear sets 640 and 650. Theoutput shaft 19 is continuously connected with members of both subsets660 and 661.

[0154] As mentioned above, the first and second input clutches 662, 663are alternatively engaged for transmitting power from the input shaft 17to transmission subset 660 or transmission subset 661. The first andsecond input clutches 662, 663 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 660, 661 prior to engagingthe respective input clutches 662, 663. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms664, 665, 666, 667, 668, 669, 670 and 671. The torque transmittingmechanisms 664, 665, 668 and 669 comprise braking synchronizers, and thetorque transmitting mechanisms 666, 667, 670 and 671 comprise rotatingsynchronizers.

[0155] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 660, 661 (i.e. through the clutch662 to the sun gear member 622 and through the clutch 663 to the sungear member 642). The planet carrier assembly member 626 is continuouslyconnected with the sun gear member 632 through the interconnectingmember 672. The planet carrier assembly member 646 is continuouslyconnected with the ring gear member 634 and the output shaft 19 throughthe interconnecting member 674. The ring gear member 644 is continuouslyconnected with the planet carrier assembly member 656 through theinterconnecting member 676.

[0156] The planet carrier assembly member 626 is selectively connectablewith the transmission housing 680 through the braking synchronizer 664.The planet carrier assembly member 636 is selectively connectable withthe transmission housing 680 through the braking synchronizer 665. Thering gear member 624 is selectively connectable with the planet carrierassembly member 636 through the synchronizer 666. The sun gear member622 is selectively connectable with the planet carrier assembly member636 through the synchronizer 667. The sun gear member 652 is selectivelyconnectable with the transmission housing 680 through the brakingsynchronizer 668. The ring gear member 654 is selectively connectablewith the transmission housing 680 through the braking synchronizer 669.The planet carrier assembly member 646 is selectively connectable withthe sun gear member 652 through the synchronizer 670. The planet carrierassembly member 646 is selectively connectable with the ring gear member654 through the synchronizer 671.

[0157] As shown in FIG. 7b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The ratio values given are byway example and are established utilizing the ring gear/sun gear toothratios given in FIG. 7b. For example, the R1/S2 value is the tooth ratioof the planetary gear set 620; the R2/S2 value is the tooth ratio of theplanetary gear set 630; the R3/S3 value is the tooth ratio of theplanetary gear set 640; and the R4/S4 value is the tooth ratio of theplanetary gear set 650. The ratio steps between adjacent forward ratiosand the reverse to first ratio are also given in FIG. 7b.

[0158] Those skilled in the art will, upon reviewing the truth table ofFIG. 7b, recognize that the numerical values of the reverse and firstforward speed ratios are determined utilizing the ring gear/sun geartooth ratios of the planetary gear sets 640, 650. The numerical valuesof the second and fourth forward speed ratios are determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 620, 630.The numerical value of the third forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set640. The numerical value of the fifth forward speed ratio is 1. Thenumerical value of the sixth forward speed ratio is determined utilizingthe ring gear/sun gear tooth ratio of the planetary gear set 630.

[0159] A powertrain 710, shown in FIG. 8a, has the conventional engine12, a planetary transmission 714, and the conventional final drivemechanism 16. The engine 12 is continuously connected with the inputshaft 17. The planetary transmission 714 is drivingly connected with thefinal drive mechanism 16 through the output shaft 19. The planetarytransmission 714 includes a planetary gear arrangement 718 that has afirst planetary gear set 720, a second planetary gear set 730, a thirdplanetary gear set 740, and a fourth planetary gear set 750.

[0160] The planetary gear set 720 includes a sun gear member 722, a ringgear member 724, and a planet carrier assembly member 726. The planetcarrier assembly member 726 includes a plurality of intermeshing piniongears 727, 728 rotatably mounted on a carrier member 729 and disposed inmeshing relationship with the ring gear member 724 and the sun gearmember 722, respectively.

[0161] The planetary gear set 730 includes a sun gear member 732, a ringgear member 734, and a planet carrier assembly member 736. The planetcarrier assembly member 736 includes a plurality of intermeshing piniongears 737, 738 rotatably mounted on a carrier member 739 and disposed inmeshing relationship with the ring gear member 734 and the sun gearmember 732, respectively.

[0162] The planetary gear set 740 includes a sun gear member 742, a ringgear member 744, and a planet carrier assembly member 746. The planetcarrier assembly member 746 includes a plurality of pinion gears 747rotatably mounted on a carrier member 749 and disposed in meshingrelationship with both the sun gear member 742 and the ring gear member744.

[0163] The planetary gear set 750 includes a sun gear member 752, a ringgear member 754, and a planet carrier assembly member 756. The planetcarrier assembly member 756 includes a plurality of pinion gears 757rotatably mounted on a carrier member 759 and disposed in meshingrelationship with both the sun gear member 752 and the ring gear member754.

[0164] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 720, 730, 740 and 750 are divided into firstand second transmission subsets 760, 761 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 760 includes planetary gear sets 720 and 730, andtransmission subset 761 includes planetary gear sets 740 and 750. Theoutput shaft 19 is continuously connected with members of both subsets760 and 761.

[0165] As mentioned above, the first and second input clutches 762, 763are alternatively engaged for transmitting power from the input shaft 17to transmission subset 760 or transmission subset 761. The first andsecond input clutches 762, 763 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 760, 761 prior to engagingthe respective input clutches 762, 763. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms764, 765, 766, 767, 768, 769, 770 and 771. The torque transmittingmechanisms 764, 765, 768 and 769 comprise braking synchronizers, and thetorque transmitting mechanisms 766, 767, 770 and 771 comprise rotatingsynchronizers.

[0166] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 760, 761 (i.e. through the clutch762 to the sun gear member 722 and through the clutch 763 to the ringgear member 744). The ring gear member 724 is continuously connectedwith the sun gear member 732 through the interconnecting member 772. Theplanet carrier assembly member 746 is continuously connected with thering gear member 734 and the output shaft 19 through the interconnectingmember 774. The sun gear member 742 is continuously connected with thesun gear member 752 through the interconnecting member 776.

[0167] The ring gear member 724 is selectively connectable with thetransmission housing 780 through the braking synchronizer 764. Theplanet carrier assembly member 726 is selectively connectable with thetransmission housing 780 through the braking synchronizer 765. Theplanet carrier assembly member 726 is selectively connectable with theplanet carrier assembly member 736 through the synchronizer 766. The sungear member 722 is selectively connectable with the planet carrierassembly member 736 through the synchronizer 767. The ring gear member754 is selectively connectable with the transmission housing 780 throughthe braking synchronizer 768. The planet carrier assembly member 756 isselectively connectable with the transmission housing 780 through thebraking synchronizer 769. The planet carrier assembly member 746 isselectively connectable with the ring gear member 754 through thesynchronizer 770. The planet carrier assembly member 746 is selectivelyconnectable with the planet carrier assembly member 756 through thesynchronizer 771.

[0168] As shown in FIG. 8b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. Also given in the truth table isa set of numerical values that are attainable with the present inventionutilizing the ring gear/sun gear tooth ratios given in FIG. 8b. TheR1/S1 value is the tooth ratio of the planetary gear set 720; the R2/S2value is the tooth ratio of the planetary gear set 730; the R3/S3 valueis the tooth ratio of the planetary gear set 740; and the R4/S4 value isthe tooth ratio of the planetary gear set 750.

[0169]FIG. 8b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.75.

[0170] Those skilled in the art will recognize that the numerical valuesof the reverse, first and fifth forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets720, 730. The numerical value of the second forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 740, 750. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 730. The numerical value of the fourth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 740. The numerical value of the sixth forwardspeed ratio is 1.

[0171] A powertrain 810, shown in FIG. 9a, has the conventional engine12, a planetary transmission 814, and the final drive mechanism 16. Theengine 12 is continuously connected with the input shaft 17. Theplanetary transmission 814 is drivingly connected with final drivemechanism 16 through output shaft 19. The planetary transmission 814includes a planetary gear arrangement 818 that has a first planetarygear set 820, a second planetary gear set 830, a third planetary gearset 840, and fourth planetary gear set 850.

[0172] The planetary gear set 820 includes a sun gear member 822, a ringgear member 824, and a planet carrier assembly member 826. The planetcarrier assembly member 826 includes a plurality of intermeshing piniongears 827, 828 rotatably mounted on a carrier member 829 and disposed inmeshing relationship with the ring gear member 824 and the sun gearmember 822, respectively.

[0173] The planetary gear set 830 includes a sun gear member 832, a ringgear member 834, and a planet carrier assembly member 836. The planetcarrier assembly member 836 includes a plurality of pinion gears 837rotatably mounted on a carrier member 839 and disposed in meshingrelationship with both the sun gear member 832 and the ring gear member834.

[0174] The planetary gear set 840 includes a sun gear member 842, a ringgear member 844, and a planet carrier assembly member 846. The planetcarrier assembly member 846 includes a plurality of pinion gears 847rotatably mounted on a carrier member 849 and disposed in meshingrelationship with both the sun gear member 842 and the ring gear member844.

[0175] The planetary gear set 850 includes a sun gear member 852, a ringgear member 854, and a planet carrier assembly member 856. The planetcarrier assembly member 856 includes a plurality of intermeshing piniongears 857, 858 rotatably mounted on a carrier member 859 and disposed inmeshing relationship with the ring gear member 854 and the sun gearmember 852, respectively.

[0176] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 820, 830, 840 and 850 are divided into firstand second transmission subsets 860, 861 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 860 includes planetary gear sets 820 and 830, andtransmission subset 861 includes planetary gear sets 840 and 850. Theoutput shaft 19 is continuously connected with members of both subsets860 and 861.

[0177] As mentioned above, the first and second input clutches 862, 863are alternatively engaged for transmitting power from the input shaft 17to transmission subset 860 or transmission subset 861. The first andsecond input clutches 862, 863 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratioselection is preselected within the transmission subsets 860, 861 priorto engaging the respective input clutches 862, 863. The preselection isachieved by means of electronically controlled synchronizers. As shown,the planetary gear arrangement includes eight torque transmittingmechanisms 864, 865, 866, 867, 868, 869, 870 and 871. The torquetransmitting mechanisms 864, 865, 868 and 869 comprise brakingsynchronizers, and the torque transmitting mechanisms 866, 867, 870 and871 comprise rotating synchronizers.

[0178] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 860, 861 (i.e. through the clutch862 to the sun gear member 822 and through the clutch 863 to the sungear member 842). The planet carrier assembly member 826 is continuouslyconnected with the sun gear member 832 through the interconnectingmember 872. The planet carrier assembly member 846 is continuouslyconnected with the ring gear member 834 and the output shaft 19 throughthe interconnecting member 874. The ring gear member 844 is continuouslyconnected with the planet carrier assembly member 856 through theinterconnecting member 876.

[0179] The planet carrier assembly member 826 is selectively connectablewith the transmission housing 880 through the braking synchronizer 864.The ring gear member 824 is selectively connectable with thetransmission housing 880 through the braking synchronizer 865. The sungear member 822 is selectively connectable with the planet carrierassembly member 836 through the synchronizer 866. The ring gear member824 is selectively connectable with the planet carrier assembly member836 through the synchronizer 867. The sun gear member 852 is selectivelyconnectable with the transmission housing 880 through the brakingsynchronizer 868. The ring gear member 854 is selectively connectablewith the transmission housing 880 through the braking synchronizer 869.The planet carrier assembly member 846 is selectively connectable withthe sun gear member 852 through the synchronizer 870. The planet carrierassembly member 846 is selectively connectable with the ring gear member854 through the synchronizer 871.

[0180] As shown in FIG. 9b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. A sample of numerical values forthe individual ratios is also given in the truth table of FIG. 9b. Thesenumerical values have been calculated using the ring gear/sun gear toothratios also given by way of example in FIG. 9b. The R1/S1 value is thetooth ratio of the planetary gear set 820; the R2/S2 value is the toothratio of planetary gear set 830; the R3/S3 value is the tooth ratio ofthe planetary gear set 840; and the R4/S4 value is the tooth ratio ofthe planetary gear set 850. FIG. 9b also describes the ratio stepsbetween adjacent forward ratios and between the reverse and firstforward ratio. For example, the ratio step between the first and secondforward ratios is 1.64.

[0181] Those skilled in the art will recognize that the numerical valuesof the reverse and first forward speed ratios are determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 840, 850.The numerical values of the second and fourth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 820, 830. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 840. The numerical value of the fifth forwardspeed ratio is 1. The numerical value of the sixth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 830.

[0182] Referring to FIG. 10a, a powertrain 910 is shown having aconventional engine 12, a planetary transmission 914, and a conventionalfinal drive mechanism 16. The planetary transmission 914 includes aninput shaft 17 connected with the engine 12, a planetary geararrangement 918, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 918 includesfour planetary gear sets 920, 930, 940 and 950.

[0183] The planetary gear set 920 includes a sun gear member 922, a ringgear member 924, and a planet carrier assembly member 926. The planetcarrier assembly member 926 includes a plurality of intermeshing piniongears 927, 928 rotatably mounted on a carrier member 929 and disposed inmeshing relationship with the ring gear member 924 and the sun gearmember 922, respectively.

[0184] The planetary gear set 930 includes a sun gear member 932, a ringgear member 934, and a planet carrier assembly member 936. The planetcarrier assembly member 936 includes a plurality of pinion gears 937rotatably mounted on a carrier member 939 and disposed in meshingrelationship with both the sun gear member 932 and the ring gear member934.

[0185] The planetary gear set 940 includes a sun gear member 942, a ringgear member 944, and a planet carrier assembly member 946. The planetcarrier assembly member 946 includes a plurality of pinion gears 947rotatably mounted on a carrier member 949 and disposed in meshingrelationship with both the sun gear member 942 and the ring gear member944.

[0186] The planetary gear set 950 includes a sun gear member 952, a ringgear member 954, and a planet carrier assembly member 956. The planetcarrier assembly member 956 includes a plurality of intermeshing piniongears 957, 958 rotatably mounted on a carrier member 959 and disposed inmeshing relationship with the ring gear member 954 and the sun gearmember 952, respectively.

[0187] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 920, 930, 940 and 950 are divided into firstand second transmission subsets 960, 961 which are alternatively engagedto provide odd number and even number speed ranges, respectively.Transmission subset 960 includes planetary gear sets 920 and 930, andtransmission subset 961 includes planetary gear sets 940 and 950. Theoutput shaft 19 is continuously connected with members of both subsets960 and 961.

[0188] As mentioned above, the first and second input clutches 962, 963are alternatively engaged for transmitting power from the input shaft 17to transmission subset 960 or transmission subset 961. The first andsecond input clutches 962, 963 are controlled electronically, and thedisengaged input clutch is gradually engaged while the engaged inputclutch is gradually disengaged to facilitate transfer of power from onetransmission subset to another. In this manner, shift quality ismaintained, as in an automatic transmission, while providing better fueleconomy because no torque converter is required, and hydraulicsassociated with “wet” clutching are eliminated. All speed ratios arepreselected within the transmission subsets 960, 961 prior to engagingthe respective input clutches 962, 963. The preselection is achieved bymeans of electronically controlled synchronizers. As shown, theplanetary gear arrangement includes eight torque transmitting mechanisms964, 965, 966, 967, 968, 969, 970 and 971. The torque transmittingmechanisms 964, 965, 968 and 969 comprise braking synchronizers, and thetorque transmitting mechanisms 966, 967, 970 and 971 comprise rotatingsynchronizers.

[0189] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 960, 961 (i.e. through the clutch962 to the sun gear member 922 and through the clutch 963 to the sungear member 942). The planet carrier assembly member 926 is continuouslyconnected with the sun gear member 932 through the interconnectingmember 972. The planet carrier assembly member 946 is continuouslyconnected with the ring gear member 934 and the output shaft 19 throughthe interconnecting member 974. The ring gear member 944 is continuouslyconnected with the planet carrier assembly member 956 through theinterconnecting member 976.

[0190] The planet carrier assembly member 926 is selectively connectablewith the transmission housing 980 through the braking synchronizer 964.The planet carrier assembly member 936 is selectively connectable withthe transmission housing 980 through the braking synchronizer 965. Thering gear member 924 is selectively connectable with the planet carrierassembly member 936 through the synchronizer 966. The sun gear member922 is selectively connectable with the planet carrier assembly member936 through the synchronizer 967. The sun gear member 952 is selectivelyconnectable with the transmission housing 980 through the brakingsynchronizer 968. The ring gear member 954 is selectively connectablewith the transmission housing 980 through the braking synchronizer 969.The planet carrier assembly member 946 is selectively connectable withthe sun gear member 952 through the synchronizer 970. The planet carrierassembly member 946 is selectively connectable with the ring gear member954 through the synchronizer 971.

[0191] As shown in FIG. 10b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 10b. TheR1/S1 value is the tooth ratio of the planetary gear set 920; the R2/S2value is the tooth ratio of the planetary gear set 930; the R3/S3 valueis the tooth ratio of the planetary gear set 940; and the R4/S4 value isthe tooth ratio of the planetary gear set 950.

[0192] Those skilled in the art, upon reviewing the engagementcombinations, will recognize that the numerical values of reverse andfirst forward speed ratios are determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 940, 950. The numericalvalues of the second and fourth forward speed ratios are determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets920, 930. The numerical value of the third forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratio of the planetarygear set 940. The numerical value of the fifth forward speed ratio is 1.The numerical value of the sixth forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set930.

[0193] Referring to FIG. 11a, a powertrain 1010 is shown having aconventional engine 12, a planetary transmission 1014, and aconventional final drive mechanism 16. The planetary transmission 1014includes an input shaft 17 connected with the engine 12, a planetarygear arrangement 1018, and an output shaft 19 continuously connectedwith the final drive mechanism 16. The planetary gear arrangement 1018includes four planetary gear sets 1020, 1030, 1040 and 1050.

[0194] The planetary gear set 1020 includes a sun gear member 1022, aring gear member 1024, and a planet carrier assembly member 1026. Theplanet carrier assembly member 1026 includes a plurality of intermeshingpinion gears 1027, 1028 rotatably mounted on a carrier member 1029 anddisposed in meshing relationship with the ring gear member 1024 and thesun gear member 1022, respectively.

[0195] The planetary gear set 1030 includes a sun gear member 1032, aring gear member 1034, and a planet carrier assembly member 1036. Theplanet carrier assembly member 1036 includes a plurality of pinion gears1037 rotatably mounted on a carrier member 1039 and disposed in meshingrelationship with both the sun gear member 1032 and the ring gear member1034.

[0196] The planetary gear set 1040 includes a sun gear member 1042, aring gear member 1044, and a planet carrier assembly member 1046. Theplanet carrier assembly member 1046 includes a plurality of intermeshingpinion gears 1047, 1048 rotatably mounted on a carrier member 1049 anddisposed in meshing relationship with the ring gear member 1044 and thesun gear member 1042, respectively.

[0197] The planetary gear set 1050 includes a sun gear member 1052, aring gear member 1054, and a planet carrier assembly member 1056. Theplanet carrier assembly member 1056 includes a plurality of pinion gears1057 rotatably mounted on a carrier member 1059 and disposed in meshingrelationship with both the sun gear member 1052 and the ring gear member1054.

[0198] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 1020, 1030, 1040 and 1050 are divided intofirst and second transmission subsets 1060, 1061 which are alternativelyengaged to provide odd number and even number speed ranges,respectively. Transmission subset 1060 includes planetary gear sets 1020and 1030, and transmission subset 1061 includes planetary gear sets 1040and 1050. The output shaft 19 is continuously connected with members ofboth subsets 1060 and 1061.

[0199] As mentioned above, the first and second input clutches 1062,1063 are alternatively engaged for transmitting power from the inputshaft 17 to transmission subset 1060 or transmission subset 1061. Thefirst and second input clutches 1062, 1063 are controlledelectronically, and the disengaged input clutch is gradually engagedwhile the engaged input clutch is gradually disengaged to facilitatetransfer of power from one transmission subset to another. In thismanner, shift quality is maintained, as in an automatic transmission,while providing better fuel economy because no torque converter isrequired, and hydraulics associated with “wet” clutching are eliminated.All speed ratios are preselected within the transmission subsets 1060,1061 prior to engaging the respective input clutches 1062, 1063. Thepreselection is achieved by means of electronically controlledsynchronizers. As shown, the planetary gear arrangement includes eighttorque transmitting mechanisms 1064, 1065, 1066, 1067, 1068, 1069, 1070and 1071. The torque transmitting mechanisms 1064, 1065, 1068 and 1069comprise braking synchronizers, and the torque transmitting mechanisms1066, 1067, 1070 and 1071 comprise rotating synchronizers.

[0200] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 1060, 1061 (i.e. through theclutch 1062 to the sun gear member 1022 and through the clutch 1063 tothe ring gear member 1044). The planet carrier assembly member 1026 iscontinuously connected with the sun gear member 1032 through theinterconnecting member 1072. The planet carrier assembly member 1046 iscontinuously connected with the ring gear member 1034 and the outputshaft 19 through the interconnecting member 1074. The sun gear member1042 is continuously connected with the sun gear member 1052 through theinterconnecting member 1076.

[0201] The planet carrier assembly member 1026 is selectivelyconnectable with the transmission housing 1080 through the brakingsynchronizer 1064. The ring gear member 1024 is selectively connectablewith the transmission housing 1080 through the braking synchronizer1065. The sun gear member 1022 is selectively connectable with theplanet carrier assembly member 1036 through the synchronizer 1066. Thering gear member 1024 is selectively connectable with the planet carrierassembly member 1036 through the synchronizer 1067. The ring gear member1054 is selectively connectable with the transmission housing 1080through the braking synchronizer 1068. The planet carrier assemblymember 1056 is selectively connectable with the transmission housing1080 through the braking synchronizer 1069. The planet carrier assemblymember 1046 is selectively connectable with the ring gear member 1054through the synchronizer 1070. The planet carrier assembly member 1046is selectively connectable with the planet carrier assembly member 1056through the synchronizer 1071.

[0202] As shown in FIG. 11b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 11b. TheR1/S1 value is the tooth ratio of the planetary gear set 1020; the R2/S2value is the tooth ratio of the planetary gear set 1030; the R3/S3 valueis the tooth ratio of the planetary gear set 1040; and the R4/S4 valueis the tooth ratio of the planetary gear set 1050.

[0203] Those skilled in the art, upon reviewing the engagementcombinations, will recognize that the numerical values of the reverseand first forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 1040, 1050. Thenumerical values of the second and sixth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear set 1020, 1030. The numerical value of the third forwardspeed ratio is 1. The numerical value of the fourth forward speed ratiois determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 1030. The numerical value of the fifth forward speedratio is determined utilizing the ring gear/sun gear tooth ratio of theplanetary gear set 1040.

[0204] Referring to FIG. 12a, a powertrain 1110 is shown having aconventional engine 12, a planetary transmission 1114, and aconventional final drive mechanism 16. The planetary transmission 1114includes an input shaft 17 connected with the engine 12, a planetarygear arrangement 1118, and an output shaft 19 continuously connectedwith the final drive mechanism 16. The planetary gear arrangement 1118includes four planetary gear sets 1120, 1130, 1140 and 1150.

[0205] The planetary gear set 1120 includes a sun gear member 1122, aring gear member 1124, and a planet carrier assembly member 1126. Theplanet carrier assembly member 1126 includes a plurality of intermeshingpinion gears 1127, 1128 rotatably mounted on a carrier member 1129 anddisposed in meshing relationship with the ring gear member 1124 and thesun gear member 1122, respectively.

[0206] The planetary gear set 1130 includes a sun gear member 1132, aring gear member 1134, and a planet carrier assembly member 1136. Theplanet carrier assembly member 1136 includes a plurality of intermeshingpinion gears 1137, 1138 rotatably mounted on a carrier member 1139 anddisposed in meshing relationship with the ring gear member 1134 and thesun gear member 1132, respectively.

[0207] The planetary gear set 1140 includes a sun gear member 1142, aring gear member 1144, and a planet carrier assembly member 1146. Theplanet carrier assembly member 1146 includes a plurality of pinion gears1147 rotatably mounted on a carrier member 1149 and disposed in meshingrelationship with both the sun gear member 1142 and the ring gear member1144.

[0208] The planetary gear set 1150 includes a sun gear member 1152, aring gear member 1154, and a planet carrier assembly member 1156. Theplanet carrier assembly member 1156 includes a plurality of pinion gears1157 rotatably mounted on a carrier member 1159 and disposed in meshingrelationship with both the sun gear member 1152 and the ring gear member1154.

[0209] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 1120, 1130, 1140 and 1150 are divided intofirst and second transmission subsets 1160, 1161 which are alternativelyengaged to provide odd number and even number speed ranges,respectively. Transmission subset 1160 includes planetary gear sets 1120and 1130, and transmission subset 1161 includes planetary gear sets 1140and 1150. The output shaft 19 is continuously connected with members ofboth subsets 1160 and 1161.

[0210] As mentioned above, the first and second input clutches 1162,1163 are alternatively engaged for transmitting power from the inputshaft 17 to transmission subset 1160 or transmission subset 1061. Thefirst and second input clutches 1162, 1163 are controlledelectronically, and the disengaged input clutch is gradually engagedwhile the engaged input clutch is gradually disengaged to facilitatetransfer of power from one transmission subset to another. In thismanner, shift quality is maintained, as in an automatic transmission,while providing better fuel economy because no torque converter isrequired, and hydraulics associated with “wet” clutching are eliminated.All speed ratios are preselected within the transmission subsets 1160,1161 prior to engaging the respective input clutches 1162, 1163. Thepreselection is achieved by means of electronically controlledsynchronizers. As shown, the planetary gear arrangement includes eighttorque transmitting mechanisms 1164, 1165, 1166, 1167, 1168, 1169, 1170and 1171. The torque transmitting mechanisms 1164, 1165, 1168 and 1169comprise braking synchronizers, and the torque transmitting mechanisms1166, 1167, 1170 and 1171 comprise rotating synchronizers.

[0211] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 1160, 1161 (i.e. through theclutch 1162 to the sun gear member 1122 and through the clutch 1163 tothe sun gear member 1142). The ring gear member 1124 is continuouslyconnected with the sun gear member 1132 through the interconnectingmember 1172. The planet carrier assembly member 1146 is continuouslyconnected with the ring gear member 1134 and the output shaft 19 throughthe interconnecting member 1174. The ring gear member 1144 iscontinuously connected with the planet carrier assembly member 1156through the interconnecting member 1176.

[0212] The ring gear member 1124 is selectively connectable with thetransmission housing 1180 through the braking synchronizer 1164. Theplanet carrier assembly member 1126 is selectively connectable with thetransmission housing 1180 through the braking synchronizer 1165. Theplanet carrier assembly member 1126 is selectively connectable with theplanet carrier assembly member 1136 through the synchronizer 1166. Thesun gear member 1122 is selectively connectable with the planet carrierassembly member 1136 through the synchronizer 1167. The sun gear member1152 is selectively connectable with the transmission housing 1180through the braking synchronizer 1168. The ring gear member 1154 isselectively connectable with the transmission housing 1180 through thebraking synchronizer 1169. The planet carrier assembly member 1146 isselectively connectable with the sun gear member 1152 through thesynchronizer 1170. The planet carrier assembly member 1146 isselectively connectable with the ring gear member 1154 through thesynchronizer 1171.

[0213] As shown in FIG. 12b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 12b. TheR1/S1 value is the tooth ratio of the planetary gear set 1120; the R2/S2value is the tooth ratio of the planetary gear set 1130; the R3/S3 valueis the tooth ratio of the planetary gear set 1140; and the R4/S4 valueis the tooth ratio of the planetary gear set 1150.

[0214] Those skilled in the art, upon reviewing the engagementcombinations, will recognize that the numerical values of the reverse,first and fifth forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 1120, 1130. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set1140. The numerical value of the third forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratio of the planetary gear set1130. The numerical value of the fourth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 1140, 1150. The numerical value of the sixth forwardspeed ratio is 1.

[0215] Referring to FIG. 13a, a powertrain 1210 is shown having aconventional engine 12, a planetary transmission 1214, and aconventional final drive mechanism 16. The planetary transmission 1214includes an input shaft 17 connected with the engine 12, a planetarygear arrangement 1218, and an output shaft 19 continuously connectedwith the final drive mechanism 16. The planetary gear arrangement 1218includes four planetary gear sets 1220, 1230, 1240 and 1250.

[0216] The planetary gear set 1220 includes a sun gear member 1222, aring gear member 1224, and a planet carrier assembly member 1226. Theplanet carrier assembly member 1226 includes a plurality of intermeshingpinion gears 1227, 1228 rotatably mounted on a carrier member 1229 anddisposed in meshing relationship with the ring gear member 1224 and thesun gear member 1222, respectively.

[0217] The planetary gear set 1230 includes a sun gear member 1232, aring gear member 1234, and a planet carrier assembly member 1236. Theplanet carrier assembly member 1236 includes a plurality of intermeshingpinion gears 1237, 1238 rotatably mounted on a carrier member 1239 anddisposed in meshing relationship with the ring gear member 1234 and thesun gear member 1232, respectively.

[0218] The planetary gear set 1240 includes a sun gear member 1242, aring gear member 1244, and a planet carrier assembly member 1246. Theplanet carrier assembly member 1246 includes a plurality of pinion gears1247 rotatably mounted on a carrier member 1249 and disposed in meshingrelationship with both the sun gear member 1242 and the ring gear member1244.

[0219] The planetary gear set 1250 includes a sun gear member 1252, aring gear member 1254, and a planet carrier assembly member 1256. Theplanet carrier assembly member 1256 includes a plurality of pinion gears1257 rotatably mounted on a carrier member 1259 and disposed in meshingrelationship with both the sun gear member 1252 and the ring gear member1254.

[0220] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 1220, 1230, 1240 and 1250 are divided intofirst and second transmission subsets 1260, 1261 which are alternativelyengaged to provide odd number and even number speed ranges,respectively. Transmission subset 1260 includes planetary gear sets 1220and 1230, and transmission subset 1261 includes planetary gear sets 1240and 1250. The output shaft 19 is continuously connected with members ofboth subsets 1260 and 1261.

[0221] As mentioned above, the first and second input clutches 1262,1263 are alternatively engaged for transmitting power from the inputshaft 17 to transmission subset 1260 or transmission subset 1261. Thefirst and second input clutches 1262, 1263 are controlledelectronically, and the disengaged input clutch is gradually engagedwhile the engaged input clutch is gradually disengaged to facilitatetransfer of power from one transmission subset to another. In thismanner, shift quality is maintained, as in an automatic transmission,while providing better fuel economy because no torque converter isrequired, and hydraulics associated with “wet” clutching are eliminated.All speed ratios are preselected within the transmission subsets 1260,1261 prior to engaging the respective input clutches 1262, 1263. Thepreselection is achieved by means of electronically controlledsynchronizers. As shown, the planetary gear arrangement includes eighttorque transmitting mechanisms 1264, 1265, 1266, 1267, 1268, 1269, 1270and 1271. The torque transmitting mechanisms 1264, 1265, 1268 and 1269comprise braking synchronizers, and the torque transmitting mechanisms1266, 1267, 1270 and 1271 comprise rotating synchronizers.

[0222] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 1260, 1261 (i.e. through theclutch 1262 to the sun gear member 1232 and through the clutch 1263 tothe sun gear member 1242). The sun gear member 1222 is continuouslyconnected with the planet carrier assembly member 1236 through theinterconnecting member 1272. The planet carrier assembly member 1246 iscontinuously connected with the ring gear member 1224 and the outputshaft 19 through the interconnecting member 1274. The ring gear member1244 is continuously connected with the sun gear member 1252 through theinterconnecting member 1276.

[0223] The sun gear member 1222 is selectively connectable with thetransmission housing 1280 through the braking synchronizer 1264. Theplanet carrier assembly member 1226 is selectively connectable with thetransmission housing 1280 through the braking synchronizer 1265. Theplanet carrier assembly member 1226 is selectively connectable with thering gear member 1234 through the synchronizer 1266. The ring gearmember 1224 is selectively connectable with the ring gear member 1234through the synchronizer 1267. The ring gear member 1254 is selectivelyconnectable with the transmission housing 1280 through the brakingsynchronizer 1268. The planet carrier assembly member 1256 isselectively connectable with the transmission housing 1280 through thebraking synchronizer 1269. The planet carrier assembly member 1246 isselectively connectable with the ring gear member 1254 through thesynchronizer 1270. The planet carrier assembly member 1246 isselectively connectable with the planet carrier assembly member 1256through the synchronizer 1271.

[0224] As shown in FIG. 13b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide six forwardspeed ratios and a reverse speed ratio. The truth table also provides aset of examples for the numerical values for each of the reverse andforward speed ratios. These numerical values have been determinedutilizing the ring gear/sun gear tooth ratios given in FIG. 13b. TheR1/S1 value is the tooth ratio of the planetary gear set 1220; the R2/S2value is the tooth ratio of the planetary gear set 1230; the R3/S3 valueis the tooth ratio of the planetary gear set 1240; and the R4/S4 valueis the tooth ratio of the planetary gear set 1250.

[0225] Those skilled in the art, upon reviewing the engagementcombinations, will recognize that the numerical values of the reverseand first forward speed ratios are determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 1240, 1250. Thenumerical values of the second and sixth forward speed ratios aredetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 1220, 1230. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 1240. The numerical value of the fourthforward speed ratio is determined utilizing the ring gear/sun, geartooth ratio of the planetary gear set 1230. The numerical value of thefifth forward speed ratio is 1.

[0226]FIGS. 14a and 14 b illustrate a transmission wherein one of thetorque transmitting mechanisms from a previously described configurationis eliminated to realize five forward speed ratios and a reverse speedratio. Specifically, the powertrain 1310, shown in FIG. 14a is identicalto that shown in FIG. 10a, except that the synchronizer 967 of FIG. 10ahas been eliminated.

[0227] The powertrain 1310, shown in FIG. 14a, includes the conventionalengine 12, a planetary transmission 1314, and the conventional finaldrive mechanism 16. The engine 12 is selectively connectable with theplanetary transmission 1314 through the input shaft 17. The planetarytransmission is drivingly connected with the final drive mechanism 16through the input shaft 17. The planetary transmission 1314 includes aplanetary gear arrangement 1318 that has a first planetary gear set1320, a second planetary gear set 1330, a third planetary gear set 1340,and a fourth planetary gear set 1350.

[0228] The planetary gear set 1320 includes a sun gear member 1322, aring gear member 1324, and a planet carrier assembly member 1326. Theplanet carrier assembly member 1326 includes a plurality of intermeshingpinion gears 1327, 1328 rotatably mounted on a carrier member 1329 anddisposed in meshing relationship with the ring gear member 1324 and thesun gear member 1322, respectively.

[0229] The planetary gear set 1330 includes a sun gear member 1332, aring gear member 1334, and a planet carrier assembly member 1336. Theplanet carrier assembly member 1336 includes a plurality of pinion gears1337 rotatably mounted on a carrier member 1339 and disposed in meshingrelationship with both the sun gear member 1332 and the ring gear member1334.

[0230] The planetary gear set 1340 includes a sun gear member 1342, aring gear member 1344, and a planet carrier assembly member 1346. Theplanet carrier assembly member 1346 includes a plurality of pinion gears1347 rotatably mounted on a carrier member 1349 and disposed in meshingrelationship with both the sun gear member 1342 and the ring gear member1344.

[0231] The planetary gear set 1350 includes a sun gear member 1352, aring gear member 1354, and a planet carrier assembly member 1356. Theplanet carrier assembly member 1356 includes a plurality of intermeshingpinion gears 1357, 1358 rotatably mounted on a carrier member 1359 anddisposed in meshing relationship with the ring gear member 1354 and thesun gear member 1352, respectively.

[0232] As a result of the dual clutch arrangement of the invention, thefour planetary gear sets 1320, 1330, 1340 and 1350 are divided intofirst and second transmission subsets 1360, 1361 which are alternativelyengaged to provide odd number and even number speed ranges,respectively. Transmission subset 1360 includes planetary gear sets 1320and 1330, and transmission subset 1361 includes planetary gear sets 1340and 1350. The output shaft 19 is continuously connected with members ofboth subsets 1360 and 1361.

[0233] As mentioned above, the first and second input clutches 1362,1363 are alternatively engaged for transmitting power from the inputshaft 17 to transmission subset 1360 or transmission subset 1361. Thefirst and second input clutches 1362, 1363 are controlledelectronically, and the disengaged input clutch is gradually engagedwhile the engaged input clutch is gradually disengaged to facilitatetransfer of power from one transmission subset to another. In thismanner, shift quality is maintained, as in an automatic transmission,while providing better fuel economy because no torque converter isrequired, and hydraulics associated with “wet” clutching are eliminated.All speed ratios are preselected within the transmission subsets 1060,1061 prior to engaging the respective input clutches 1362, 1363. Thepreselection is achieved by means of electronically controlledsynchronizers. As shown, the planetary gear arrangement includes seventorque transmitting mechanisms 1364, 1365, 1366, 1368, 1369, 1370 and1371. The torque transmitting mechanism 1364, 1365, 1368, and 1369comprise braking synchronizers, and the torque transmitting mechanisms1366, 1370 and 1371 comprise rotating synchronizers.

[0234] Accordingly, the input shaft 17 is alternately connected with thefirst and second transmission subsets 1360, 1361 (i.e. through theclutch 1362 to the sun gear member 1322 and through the clutch 1363 tothe sun gear member 1342). The planet carrier assembly member 1326 iscontinuously connected with the sun gear member 1332 through theinterconnecting member 1372. The planet carrier assembly member 1346 iscontinuously connected with the ring gear member 1334 and the outputshaft 19 through the interconnecting member 1374. The ring gear member1344 is continuously connected with the planet carrier assembly member1356 through the interconnecting member 1376.

[0235] The planet carrier assembly member 1326 is selectivelyconnectable with the transmission housing 1380 through the brakingsynchronizer 1364. The planet carrier assembly member 1336 isselectively connectable with the transmission housing 1380 through thebraking synchronizer 1365. The ring gear member 1324 is selectivelyconnectable with the planet carrier assembly member 1336 through thesynchronizer 1366. The sun gear member 1352 is selectively connectablewith the transmission housing 1380 through the braking synchronizer1368. The ring gear member 1354 is selectively connectable with thetransmission housing 1380 through the braking synchronizer 1369. Theplanet carrier assembly member 1346 is selectively connectable with thesun gear member 1352 through the synchronizer 1370. The planet carrierassembly member 1346 is selectively connectable with the ring gearmember 1354 through the synchronizer 1371.

[0236] As shown in FIG. 14b, and in particular the truth table disclosedtherein, the input clutches and torque transmitting mechanisms areselectively engaged in combinations of three to provide five forwardspeed ratios and a reverse speed ratio. A sample of the numerical valuesfor the ratios is also provided in the truth table of the FIG. 14b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 14zb. The R1/S1 value is the tooth ratio ofthe planetary gear set 1320; the R2/S2 value is the tooth ratio of theplanetary gear set 1330; the R3/S3 value is the tooth ratio of theplanetary gear set 1340; and the R4/S4 value is the tooth ratio of theplanetary gear set 1350. Also given in FIG. 14b is a chart describingthe step ratios between the adjacent forward speed ratios and thereverse to first forward speed ratio.

[0237] Those skilled in the art will recognize that the numerical valuesof the reverse and first forward speed ratios are determined utilizingthe ring gear/sun gear tooth ratios of the planetary gear sets 1340,1350. The numerical values of the second and fourth forward speed ratiosare determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 1320, 1330. The numerical value of the third forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 1340. The numerical value of the fifth forwardspeed ratio is 1.

[0238] While the best modes for carrying out the invention have beendescribed in detail, those familiar with the art to which this inventionrelates will recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second, third and fourth planetary gear sets each havingfirst, second and third members; a first interconnecting membercontinuously interconnecting said first member of said first planetarygear set with said first member of said second planetary gear set; asecond interconnecting member continuously interconnecting anothermember of said first or second planetary gear set with said first memberof said third planetary gear set and with said output shaft; a thirdinterconnecting member continuously interconnecting said second memberof said third planetary gear set with said first member of said fourthplanetary gear set; a first input clutch selectively interconnectingsaid input shaft with a member of said first or second planetary gearset that is not continuously interconnected with said output shaft; asecond input clutch selectively interconnecting said input shaft withsaid third member of said third planetary gear set; first and secondtorque-transmitting mechanisms selectively interconnecting members ofsaid first or second planetary gear sets with other members of saidfirst or second planetary gear set or with said first input clutch;third and fourth torque-transmitting mechanisms selectivelyinterconnecting members of said third planetary gear set with members ofsaid fourth planetary gear set; fifth and sixth torque-transmittingmechanisms selectively interconnecting members of said first or secondplanetary gear set with a stationary member; seventh and eighthtorque-transmitting mechanisms selectively interconnecting members ofsaid fourth planetary gear set with said stationary member; and saidinput clutches and torque-transmitting mechanisms being engaged incombinations of at least three to provide at least six forward speedratios and a reverse speed ratio.
 2. The transmission defined in claim1, wherein said eight torque-transmitting mechanisms comprisesynchronizers.
 3. The transmission defined in claim 1, wherein saidfirst, second, third and fourth torque-transmitting mechanisms compriserotating synchronizers, and said fifth, sixth, seventh and eighthtorque-transmitting mechanisms comprise braking synchronizers.
 4. Thetransmission defined in claim 1, wherein said first input clutch isapplied for odd number speed ranges and said second input clutch isapplied for even number speed ranges.
 5. The transmission defined inclaim 1, wherein said first input clutch is applied for even numberspeed ranges and said second input clutch is applied for odd numberspeed ranges.
 6. The transmission defined in claim 1, wherein said firstinput clutch and said second input clutch are interchangeable to shiftfrom odd number speed ranges to even number speed ranges, and viceversa.
 7. The transmission defined in claim 1, wherein selected ones ofsaid eight torque-transmitting mechanisms are engaged prior to gearshifting to achieve shifting without torque interruptions.
 8. Thetransmission defined in claim 2, wherein at least two of saidsynchronizers comprise a double synchronizer to reduce cost and packagesize.
 9. A multi-speed transmission comprising: an input shaft; anoutput shaft; first, second, third and fourth planetary gear sets eachhaving first, second and third members; a first interconnecting membercontinuously interconnecting said first member of said first planetarygear set with said first member of said second planetary gear set; asecond interconnecting member continuously interconnecting anothermember of said first or second planetary gear set with said first memberof said third planetary gear set and with said output shaft; a thirdinterconnecting member continuously interconnecting said second memberof said third planetary gear set with said first member of said fourthplanetary gear set; a first input clutch selectively interconnectingsaid input shaft with a member of said first or second planetary gearset that is not continuously interconnected with said output shaft; asecond input clutch selectively interconnecting said input shaft withsaid third member of said third planetary gear set; and eighttorque-transmitting mechanisms for selectively interconnecting saidmembers of said first, second, third or fourth planetary gear sets withsaid first or second input clutch, said output shaft, said first, secondor third interconnecting member, a stationary member or with othermembers of said planetary gear sets, said eight torque-transmittingmechanisms being engaged in combinations of at least three to establishat least six forward speed ratios and a reverse speed ratio between saidinput shaft and said output shaft.
 10. The transmission defined in claim9, wherein first and second of said eight torque-transmitting mechanismsare selectively operable for interconnecting members of said first orsecond planetary gear sets with other members of said first or secondplanetary gear sets, or with said first input clutch.
 11. Thetransmission defined in claim 9, wherein third and fourth of said eighttorque-transmitting mechanisms are selectively operable forinterconnecting members of said third planetary gear set with members ofsaid fourth planetary gear set.
 12. The transmission defined in claim 9,wherein fifth and sixth of said eight torque-transmitting mechanisms areoperable for selectively interconnecting members of said first or secondplanetary gear set with said stationary member.
 13. The transmissiondefined in claim 9, wherein seventh and eighth of said eighttorque-transmitting mechanisms are operable for selectivelyinterconnecting members of said fourth planetary gear set with saidstationary member.
 14. The transmission defined in claim 9, wherein saidmembers of said planetary gear sets include a sun gear member, a ringgear member and a planet carrier assembly member, and wherein planetcarrier assembly members of a plurality of said planetary gear sets areof the single pinion type.
 15. The transmission defined in claim 9,wherein said members of said planetary gear sets include a sun gearmember, a ring gear member and a planet carrier assembly member, andwherein planet carrier assembly members of a plurality of said planetarygear sets are of the double pinion type.
 16. The transmission defined inclaim 9, wherein each of said eight torque-transmitting mechanismscomprises a synchronizer.
 17. The transmission defined in claim 9,wherein said first input clutch is applied for odd number speed rangesand said second input clutch is applied for even number speed ranges.18. The transmission defined in claim 9, wherein said first input clutchis applied for even number speed ranges and said second input clutch isapplied for odd number speed ranges.
 19. The transmission defined inclaim 9, wherein selected ones of said eight torque-transmittingmechanisms are engaged prior to gear shifting to achieve shiftingwithout torque interruptions.
 20. A multi-speed transmission comprising:an input shaft; an output shaft; first, second, third and fourthplanetary gear sets each having first, second and third members; a firstinterconnecting member continuously interconnecting said first member ofsaid first planetary gear set with said first member of said secondplanetary gear set; a second interconnecting member continuouslyinterconnecting another member of said first or second planetary gearset with said first member of said third planetary gear set and withsaid output shaft; a third interconnecting member continuouslyinterconnecting said second member of said third planetary gear set withsaid first member of said fourth planetary gear set; a first inputclutch selectively interconnecting said input shaft with a member ofsaid first or second planetary gear set that is not continuouslyinterconnected with said output shaft; a second input clutch selectivelyinterconnecting said input shaft with said third member of said thirdplanetary gear set; and seven torque-transmitting mechanisms forselectively interconnecting said members of said first, second, third orfourth planetary gear sets with said first or second input clutch, saidoutput shaft, said first, second or third interconnecting member, astationary member or with other members of said planetary gear sets,said seven torque-transmitting mechanisms being engaged in combinationsof at least three to establish at least five forward speed ratios and areverse speed ratio between said input shaft and said output shaft. 21.The transmission defined in claim 20, wherein a first of said seventorque-transmitting mechanisms is selectively operable forinterconnecting a member of said first or second planetary gear set withanother member of said first or second planetary gear set, or with saidfirst input clutch.
 22. The transmission defined in claim 20, whereinsecond and third of said seven torque-transmitting mechanisms areselectively operable for interconnecting members of said third planetarygear set with members of said fourth planetary gear set.
 23. Thetransmission defined in claim 20, wherein fourth and fifth of said seventorque-transmitting mechanisms are operable for selectivelyinterconnecting members of said first or second planetary gear sets withsaid stationary member.
 24. The transmission defined in claim 20,wherein sixth and seventh of said seven torque-transmitting mechanismsare operable for selectively interconnecting members of said fourthplanetary gear set with said stationary member.
 25. The transmissiondefined in claim 20, wherein planet carrier assembly members of aplurality of said planetary gear sets are of the single pinion type. 26.The transmission defined in claim 20, wherein planet carrier assemblymembers of a plurality of said planetary gear sets are of the doublepinion type.
 27. The transmission defined in claim 20, wherein each ofsaid seven torque-transmitting mechanisms comprises a synchronizer. 28.The transmission defined in claim 20, wherein said first input clutch isapplied for odd number speed ranges and said second input clutch isapplied for even number speed ranges.
 29. The transmission defined inclaim 20, wherein said first input clutch is applied for even numberspeed ranges and said second input clutch is applied for odd numberspeed ranges.
 30. The transmission defined in claim 20, wherein selectedones of said seven torque-transmitting mechanisms are engaged prior togear shifting to achieve shifting without torque interruptions.